which one for rear surrounds

Have b & w  cm 9 s1 fronts with cm 2 s2 center. What should I buy for surrounds cm 6 or 683 towers ?
7c1fd0ae 7541 4ad0 bc86 aee6c43107b7kennylho
The towers, no question. The extra bass and dynamic range will outperform the better tweeter, especially with room correction.